This is about the concept of annihilation in Tenet.
The concept of inverting oneself is introduced. When an individual is inverted, this person will experience the flow of time in the reverse direction. In one of the scenes, the Protagonist is about to get the "Plutonium" from Sator, and a female scientist warns him that he should not contact his forward self. Otherwise, he will be annihilated.
Further on in the movie, the Protagonist travels back to Freeport to un-invert himself where he gets into a scuffle with his forward self. Did this not count as a contact? Why was the Protagonist not annihilated?